It is well known in the art to provide wing frame sections on farm machinery such as tillage and planting equipment wherein one or more wing frame sections can be folded up relative to a central main frame section to reduce the overall width of the machine for transport. In some five-section machines, for example, hydraulic cylinders fold outer wing sections almost 180° on top of inner wing frame sections and then other lift cylinders raise the inner wing frame sections into essentially upright positions to provide a compact piece of machinery for over-the-road travel or movement through gates and the like. It is also well known to provide lost motion couplings between the various lift cylinders and their wing frame sections so that, in the field-working position, the frame sections can be hinged relative to one another as need be to accommodate changes in ground contour encountered by the different sections of the machine. While this type of “flexing” action is important during field operations, it can also create problems during unfolding operations, particularly for the outer wing sections.
In this regard, the unfolding sequence of a five-section machine, for example, is that the inner wing frame sections are the first to unfold, followed then by the outer wing frame sections. As the inner wing frame sections are lowered down to their working positions and their tools come into ground engagement, their lift cylinders continue to extend an additional amount so as to position the lost motion coupling in an intermediate position, so that the inner wing sections can flex up and down to a certain extent relative to the main section. After the inner lift cylinders are thus fully extended, the outer lift cylinders unfold the outer wing frame sections and place them in the field working position as well. However, if the outer ends of the inner wing frame sections have dipped down slightly because their tools have sunk into soft ground or the ground is inclined, the tools on the outer wing frame sections near the hinge points may dig into the ground and bear an excessive amount of the load as the outer wing frame sections pivot down into their working positions. This is a particular problem where tools such as packer wheels project back from the rear of the outer wing frame sections and are supported by linkage that allows the packer wheels to drop down below the transport wheels on the outer wing frame sections. The gangs of packer wheels may tend to flip up and/or stress the mounting frames and pivot areas of the gangs.
The present invention provides a way of holding an inner wing frame section slightly raised while the outer wing frame section is lowered into its transport position, thereby keeping packer wheel gangs or other tools on the outer wing frame section from digging or dragging into the ground as the outer wing frame section approaches its unfolded condition. In a preferred embodiment, the inner end of the inner wing lift cylinder is not fixedly mounted to the main frame section as in conventional arrangements but is instead connected to a holding cylinder that adjusts the anchor point of the inner lift cylinder. Thus, when the holding cylinder is contracted, the anchor point of the inner wing lift cylinder is positioned more inboard that usual, preventing the inner wing frame section from swinging down to a completely horizontal position when the inner lift cylinder is fully extended during unfolding. Therefore, the hinge point for the outer wing section is held in a sufficiently elevated position that the tools of the outer wing section near the hinge point are not allowed to significantly contact the ground as the outer wing frame section unfolds. Once the outer lift cylinder has fully extended, the holding cylinder extends to allow both the inner and outer wing sections to settle down to the ground and place their lost motion couplings in intermediate positions to permit the desired flexing or floating action of the wings relative to the main frame section.
In a preferred embodiment, the holding cylinder is connected between the anchor ends of the two inner lift cylinders of a five-section machine so that the holding cylinder helps both sides of the machine. Preferably, in addition to being interconnected by the holding cylinder, the anchor ends of the inner lift cylinders are also attached to the main frame section by swingable lever assemblies. Desirably, the holding cylinder is on a separate hydraulic circuit from the wing lift cylinders, or at least a circuit that can be isolated from other circuitry associated with the wing lift cylinders by sequence valves or the like so that the holding cylinder is always the first to contract during the folding sequence and the last to extend during the unfolding sequence.